The present invention relates to a male insert member having a part line free circumferential seal integrally molded therewith and a method for making same.
There is an increasing demand for mass produced, inexpensive, coupling assemblies which can be readily coupled and uncoupled and wherein at least a part of the coupling assembly such as a male insert member is attached to a disposable container or other disposable item so as to be disposed of along with the disposable container or other item after the item has been used. Such disposable coupling assemblies enable the disposable items to have a portion of the coupling assembly, such as the male insert member, included as a part of its structure or readily interconnected thereto at the time of installation of the disposable items in a fluid handling system. When it comes time to dispose of the disposable items their associated coupling portions are disposed of along with the disposable item. This allows the disposable item to be quickly connected to a system and replaced as required without necessitating that the item and/or its associated coupling portion be cleaned and sanitized as would be required in many systems if the item and/or its associated coupling portion were reused. If a reusable coupling fitting is used with a disposable item, the reuseable coupling fitting must typically be separated from the disposable item and cleaned before it is reused with another disposable item.
The liquid packaging industry is using disposable containers incorporating disposable coupling portions for handling and dispensing of beverages, inks, industrial cleaners, and detergents as well as many other types of liquids. This eliminates much of the mess often associated with the packaging and handling of fluids since fluid containers can be quickly connected to and disconnected from a fluid handling system with less spillage. Moreover, for sanitary reasons, it is very desirable to have disposable liquid containers which include a throw-away coupling portion, so as to eliminate the need to clean the container and/or coupling portion. Also, contamination of fluids can be more readily prevented and switching from one type of fluid to another. The medical market is another area where a coupling system is required which can utilize a disposable coupling fitting. A throw-away or disposable coupling fitting which can be disposed of along with the disposable item is particularly helpful in maintaining sanitary conditions which are of the utmost importance in the medical environment. With diseases, such as AIDS, this takes on even increased importance. As discussed above, disposable coupling fittings do away with the need to clean and sterilize the used item and its associated coupling portion, which is both time consuming and expensive, thereby also facilitating the reduction of medical costs.
One example of a disposable item, is the use of disposable hypothermia blankets or pads. A coupling, preferably disposable, is required to typically connect the blanket or pad to a small pump which heats and circulates water through the blanket or pad. Disposing of the heating pad does away with the need to sanitize the heating pad before being used by the next user. Ideally, when the heating pad is disposed of, the coupling portion interconnected thereto is also disposed of. There are of course endless other applications for disposable coupling fittings.
It is important that the cost of disposable coupling fittings be kept to a minimum in order to reduce the cost of the overall product. Cost can typically be reduced if the coupling is mass producible and if its structure is relatively non-complex. However, despite the need for a low cost coupling fitting, it is very important that the coupling assembly be highly reliable and not leak. Therefore disposable coupling fittings must be manufactured to relatively tight tolerances. This in turn, typically necessitates stringent quality control which can be very expensive and time consuming. Additionally, the coupling fitting must be made of a material which is compatible with the liquid environment in which it is used.
Examples of various coupling assemblies are illustrated in applicant's U.S. Pat. Nos. 4,436,125('125) and 4,630,847('847).
Typically, coupling assemblies designed for use with disposable items will include a disposable male insert member attached to the disposable item and a cooperating non-disposable female receptacle member adapted for receipt of the male insert member. A mechanical latch/lock mechanism is used to retain the two coupling members in a coupled state. The coupling male insert members typically form a fluid tight seal with the cooperating coupling female receptacle members by the use of the cylindrical seal which circumferentially surrounds the male inserts. The exterior surface of the seal cooperates with the interior surface of the female receptacle upon insertion of the male insert into the female receptacle to form a fluid tight seal. The cylindrical seal is made of elastic material which is softer than the female receptacle such that the exterior surface of the seal will be deformed by the interior walls of the female receptacle upon insertion of the male insert into the female receptacle. Accordingly a fluid tight seal is formed between the two coupling members. A separate mechanical latch mechanism is used to positively latch the male insert and the female receptacle in a coupled state since the cylindrical seal has no appreciable retention affect due to its relative elasticity and its relatively small surface area which abuts the interior surface area of the female receptacle, the male insert and the female receptacle being configured for ease of insertion (connection) and removal (disconnection). The mechanical latch mechanism will often be associated with the female receptacle, the male insert including a groove or other cavity for receipt of a latch plate or the like mounted on the female receptacle.
While the male insert is often made from molded plastic or other materials, the seal typically might be a separate and distinct cylindrical o-ring made from a rubber-like material, the o-ring being typically seated in a groove of the male insert. The seal might also be a cylindrical ring-like structure integrally molded with the male insert. Both types of seals are in use in the industry, and both types of seals are shown in applicant's prior patents. However, both types of seals have definite disadvantages as currently made.
O-ring seals are relatively expensive and can add greatly to the cost of the coupling. Moreover, o-rings generally have part lines on their inner and outer rims which can interfere with their sealing function and cause quality control problems. With respect to integrally molded seals, in normal molding practices, when molding a coupling male insert member, a part line is produced that extends longitudinally of the male insert. The part line is formed at the location where the mold elements come together to form the male insert. If the seal is of the type which is formed integral with the male insert, the seal will similarly have the part line extending there across at a right angle to the seal. During the manufacturing process, the part line of the couplings must be monitored for flash and mold mismatch in order to assure the quality of the molded coupling fittings. Also the process must be closely monitored since there can be variations in the materials used; e.g., flow characteristics, etc., which will have a substantial affect on the part line. This is particularly important the integral seal since the part line can cause a fluid leak and/or over time cause wear which will result in a fluid leak. The quality control required to monitor the coupling manufacturing process is a very expensive and time consuming one. While this might be acceptable in most coupling markets where the couplings are produced in limited numbers and are more expensive, the quality control becomes a real problem when mass producing, inexpensive, disposable coupling fittings which must meet the requirements of such industries as the liquid packaging/handling industry and the medical industry.
The applicant has discovered that by use of a molding process which creates a part line free integral seal, disposable couplings fittings can be mass produced in an inexpensive fashion and yet meet the rather rigid quality requirements of the liquid packaging/handling industry and the medical industry. Use of a part line free seal substantially eliminates the flash and mold mismatch problems present with a part line.
There are interference fittings currently in use which are molded with a part line free tapered end. The tapered end of fitting is forced into a tubing or the like made of softer material than the tapered end of the fitting so as to deform and stretch the tubing, thereby providing an interference fit between the fitting and the tubing. The tapered end with its associated undercut shoulder portion serves to both form a fluid tight seal between the fitting and the tubing and also grip the interior surface of the tubing to retain the fitting and tubing in a coupled state so as to not require the use of a mechanical latch/lock mechanism. An example of this is shown in applicant's Ser. No. 818,245, filed Jan. 13, 1986 now U.S. Pat. No. 4,703,957 issued Nov. 3, 1987. Such fittings are not practical in those applications where a two part coupling assembly is used or where the fluid flow is large, since the tensile force required to separate a coupling from its receptacle is substantial. This is undesirable for several reasons. Moreover, they do not provide for a positive latching of the fittings in a coupled state. Accordingly, it is difficult to tell when the tapered fittings and their associated tubing are securely connected in a fluid tight state. Additionally, they present a leakage problem when connecting or disconnecting from the tubing.
The present invention solves these and other problems associated with existing disposable coupling fittings.